This invention relates to the location of positions on maps.
Various systems are on the market for facilitating the location of one""s position on a map. One example, called the Silva GPS Compass, marketed by Silva Sweden AB, of Sollentuna, Sweden, is a portable device which includes a global positioning system (xe2x80x9cGPSxe2x80x9d) receiver and can display the current position of the receiver in terms of longitude and latitude with an accuracy of about 100 m under the current level of xe2x80x9cselective availabilityxe2x80x9d applied by the U.S. Department of Defense who operate GPS. When used with a map having longitude and latitude grid lines, one""s position on the map can be located. However, there are two main disadvantages with this system. First, many maps (particularly road and street atlases and steeet plans) do not have any longitude and latitude markings whatsoever. Many other maps (for example British Ordnance Survey (xe2x80x9cOSGBxe2x80x9d) maps), although having longitude and latitude markings around their border and 5 minute graticule markings on the map, do not have any longitude and latitude grid lines drawn across the map. Thus it can be difficult to locate one""s position on the map. Second, because longitude and latitude is a global co-ordinate system, much more information is provided by full longitude and latitude co-ordinates than is actually required to locate one""s position on a map covering only a minuscule part of the surface area of the planet, and this can lead to confusion. For example, the old UK Patent Office building in Southampton Buildings, off Chancery Lane, London is situated at (51xc2x030xe2x80x259xe2x80x3N, xe2x88x920xc2x006xe2x80x234xe2x80x3E), but it is difficult to locate that position on the relevant map in the OSGB 1:50,000 Landranger Second Series, Sheet 176, which covers latitudes 51xc2x019xe2x80x2N to 51xc2x041xe2x80x2N approximately and longitudes xe2x88x920xc2x003xe2x80x2E to xe2x88x920xc2x038xe2x80x2E approximately, but without any longitude and latitude grid lines. Many GPS receivers also produce co-ordinates in various map-grid systems relevant to different countries"" mapping systems. The conversion between latitude and longitude and such map-grid systems is made using known and documented algorithms. Throughout this specification, latitude and longitude is therefore used as an example of any wide-area co-ordinate system as hereinafter defined.
A system which deals with some of the above problems is foreshadowed in patent document WO-A-87/07013 and is marketed by Yeoman Marine Limited, of Lymington, Hampshire, United Kingdom, under the name xe2x80x9cNavigator""s Yeomanxe2x80x9d. Also, an accessory is available for the Silva GPS compass, called the xe2x80x9cSilva Yeoman Navimapxe2x80x9d, which has a similar effect. These systems use (a) a digitising table on which a traditional map can be placed, (b) a cursor which is movable across the map on the table and has indicators to indicate a required direction of movement, (c) a GPS receiver (or an input to receive a signal from a separate GPS receiver) from which one""s current position can be determined, and (d) a processor which determines, from the cursor position on the digitising table and the current GPS position, which way the cursor should be moved so that it is over the current position and activates the indicator lights on the cursor accordingly. Whilst this system has the advantages that it can be used with any traditional map to any scale and of any part of the world, and one""s current position can be located by following the indicators rather than thinking in terms of latitude and longitude, it does suffer from two disadvantages. First, before it can be used, the map must be manually referenced with respect to the digitising table so that the processor can translate between the latitude and longitude co-ordinates obtained from the GPS receiver and the co-ordinates of the digitiser table. Referencing can be performed by placing the cursor at two (and preferably three) positions on the chart, and at each position instructing the processor with the latitude and longitude co-ordinates of that position. Alternatively, when used for relative, rather than absolute, positioning when one""s current position on the map is known, referencing can be carried out by registering the cursor on the current known position on map and then indicating to the apparatus the north direction of the map and its scale. Second, it requires the use of a digitising table which is as large as the map, or at least as large as a folded portion of the map which is to be viewed at one time without re-referencing.
Another apparatus which deals with this problem is described in patent document WO-A-95/22742, in which a paper map is placed behind a transparent liquid crystal display which can cover the whole area of the map. The map has a mark, for example in the form of a bar code, which can be read by the apparatus and used to correlate positions on the map with latitude and longitude positions. The apparatus also includes a GPS receiver, and the current position obtained from the receiver is converted into a map position, which is then indicated on the LCD by a graphic image, such as crosshairs, to show the current position on the map. However, this apparatus suffers from a number of disadvantages. First, a liquid crystal graphic display is required which is as large as the map, which is thus expensive, cumbersome and liable to be damaged. Second, it is necessary for the map to be used opened out, and the apparatus cannot apparently deal with folded maps. Third, the apparatus can apparently be used only with single sheet maps.
One solution to these problems is to xe2x80x9ccomputerisexe2x80x9d the map. In the SkyMap system marketed by Skyforce Avionics Limited of Ramsgate, Kent, United Kingdom, which is primarily designed for aircraft navigation, a representation of the map is held in computer memory. The current position is determined using a GPS receiver, and a relevant part of the map, together with the current position, is displayed on a liquid crystal graphic display. The disadvantages of this sort of system are that (a) it would be extremely expensive if a large, high-resolution, map and colour display were to be used; and (b) many people prefer to use a traditional map. The SkyMap system also has the ability to display the full OSGB grid co-ordinates of the current position so that the position can be located on an OSGB map. However, OSGB maps are not indexed according to the grid reference covered, only according to sheet numbers, and the sheet numbers depend on the scale and series of the maps. Therefore it is not straightforward to select the appropriate map. Also, for a resolution of 100 m, the full eight digit (or two letter and six digit) OSGB grid reference is not needed and not normally used when referring to a particular 1:50,000 sheet, and therefore providing all eight digits can lead to unnecessary confusion.
The present invention is concerned with dealing with the problems mentioned above of the known systems.
In this specification, the following terms are intended to have the following meanings: xe2x80x9cTraditional mapxe2x80x9d means a map which is printed on paper, linen, plastics sheet or the like: xe2x80x9cMap co-ordinate systemxe2x80x9d means a system of co-ordinates which are normally used to define a position on a particular map, and differs from a xe2x80x9cWide-area co-ordinate systemxe2x80x9d which includes the longitude and latitude system for defining positions on the earth""s surface, but also includes other co-ordinate systems. For example, when considering a single map in the OSGB 1:50,000 series, for instance Sheet 176 mentioned above, the co-ordinates (312, 815) are co-ordinates according to the map co-ordinate system for that map, and differ not only from the co-ordinates (51.5164xc2x0N, xe2x88x920.1095xc2x0E) according to the longitude and latitude co-ordinate system but also from the full OSGB co-ordinates (5312, 1815) or (TQ, 312, 815) according to the complete wide-area OSGB coordinate system; and xe2x80x9cWide-area position transmitting systemxe2x80x9d means a system which transmits signals which can be received over a large area and which can be processed so as to determine the receiver""s position in terms of a wide-area co-ordinate system. An example of a wide-area position transmitting system is xe2x80x9cGPSxe2x80x9d, which is operated by the U.S. Departnent of Defense and comprises a couple of dozen or so transmitters which orbit the earth and transmit signals. When the signals from three or more transmitters are being received at a single site, they can be processed so as to determine the position of that site in terms of longitude and latitude. However, the term xe2x80x9cwide-area position transmitting systemxe2x80x9d is intended to include not only other satellite positioning systems, but also terrestrial positioning systems which rely on transmissions from land-based transmitters, and from which one""s position in terms of a wide-area co-ordinate system can be determined.
First and second aspects of the invention are concerned in particular with a position locating apparatus, for use with a traditional map having its own co-ordinate system distinct from a wide-area co-ordinate system and for use with conversion data associated with the map (e.g. in the form of a bar code, magnetic stripe, smart card or encoded text) from which the relationship between the map co-ordinate system and the wide-area co-ordinate system can be determined, the apparatus comprising: means for receiving the conversion data; means for receiving transmissions from a wide-area position transmitting system and determining therefrom the current position of the transmission receiving means in terms of the wide-area coordinate system; means for processing the current wide-area co-ordinate position and the conversion data to determine the current position in terms of the map co-ordinate system: and means (e.g. a display or speech synthesiser) for annunciating to a user the current map co-ordinate position. Such a system is disclosed in WO-95/22742 mentioned above.
The first aspect of the invention is characterised in that: the processing means is operable to determine the current map co-ordinate position as a coarse position relative to the map and a fine position relative to the coarse position; and the annunciating means comprises means for annunciating the coarse position and means for annunciating the fine position.
The aspect of the invention therefore provides the advantage that a form of annunciation which is suitable for coarse positioning can be used for that purpose, and another form of annunciation which is suitable for fine positioning can be used for that purpose.
In one embodiment for use with such a map which is divided up into an array of blocks, the coarse position annunciating means is preferably operable to annunciate an identity of that one of the blocks containing the current position, as in the above example xe2x80x9cBlock M 42xe2x80x9d.
For annunciating the fine position, each block could, for example, be notionally divided in ten in each of the x and y directions, and the location of the old Patent Office building could be annunciated as xe2x80x9cPage 62, Block M 42, Position (1, 7)xe2x80x9d. However, this may cause confusion, for example as to whether it means 1/10 along and 7/10 up, or 1/10 up and 7/10 along. To deal with this, and the fine position annunciating means preferably comprises a graphical display and means for activating the display to display the fine position relative to a datum point. Preferably, the display comprises a see-through display which can be registered over the identified block on the map and which is operated to indicate the current position within that block. Accordingly, the display need only be as large as a block on the map, and need not be as large as the whole map.
The apparatus may be used with such conversion data from which the area covered by the map can be determined, and in this case the processing means is preferably operable to determine whether the current position is covered by the map. In this way, invalid or inappropriate annunciations, which might confuse the user, can be avoided.
The apparatus may be used with a series of such maps and with such conversion data from which the relationship between the co-ordinate system(s) of the maps and the wide-area co-ordinate system can be determined and the area covered by each map can be determined. In this case, preferably the processing means is operable to determine (a) the identity of that map, or at least one of those maps, which cover the current position, and (b) the current position on that map in terms of the co-ordinate system of that map; and the annunciating means is operable to annunciate to the user (a) the identity of that map and (b) the current position in terms of the co-ordinate system of that map. Thus, the user can be assisted in selecting the appropriate map. Thus, for example, in the case of the OSGB 1:50,000 Landranger Second Series, the data for all two hundred and four sheets in the series may be stored, and in the case of the position mentioned above, the annunciation may be in the form xe2x80x9cSheet 176, grid block (31, 81).xe2x80x9d
This latter feature may be provided in an apparatus which does not possess the other features of the first aspect of the invention. Accordingly, the second aspect of the invention is characterised in that: the apparatus is for use with a series of such maps and for use with such conversion data from which the relationship between the co-ordinate system(s) of the maps and the wide-area co-ordinate system can be determined and the area covered by each map can be determined; the processing means is operable to determine (a) the identity of that map, or at least one of those maps, which cover the current position, and (b) the current position on that map in terms of the co-ordinate system of that map; and the annunciating means is operable to annunciate to the user (a) the identity of that map and (b) the current position in terms of the co-ordinate position of that map.
The apparatus may be used with such maps having some portions which overlap, and in this case preferably the processing mans is operable, in the case of a position falling on more than one of the maps, to determine (a) the identity of two or more of the maps which cover the current position, and (b) the current position(s) on those maps in terms of the co-ordinate system(s) of those maps; and the annunciating means is operable to annunciate to the user (a) the identities of those maps and (b) each current position in terms of the co-ordinate system of the respective map. Thus, when used with an atlas, for example, the apparatus does not force the user to turn a page when that may not be necessary.
The apparatus may be used with such maps which are not all to the same scale and with such conversion data which takes into account the different scales of the maps, and in this case preferably the processing means is operable to take into account the scale of the maps in determining the current position in terms of the map co-ordinate system(s). For example, the Geographers"" A-Z Master Atlas of Greater London, Edition 4(B), has a first set of maps on pages 2 to 160 covering Greater London to a scale of 3xe2x80x3 to 1 mile (1:21,120), a second set of maps on pages 162 to 183 covering central London to a larger scale of 9xe2x80x3 to 1 mile (1:7,040) and a third set of maps covering London and its environs to a smaller scale of 2xc2xd miles to 1xe2x80x3 (1:158,400). The site of the old UK Patent Office building off Chancery Lane is covered by all three sets of maps, on pages 62, 173 and 186, as shown in FIGS. 1, 2 and 3, respectively, of the accompanying drawings. In accordance with this feature of the invention, the position of that building could be annunciated as xe2x80x9cPage 62, Block M 42xe2x80x9d, xe2x80x9cPage 173, Block G 2xe2x80x9d and xe2x80x9cPage 186, Block (30, 80)xe2x80x9d, simultaneously, or one after another.
The apparatus may be used with such conversion data from which the relationship between the map co-ordinate system and at least one datum point of the medium on which the map is formed can he determined, and in this case one embodiment of the apparatus tier includes: a digitising surface having its own co-ordinate system means for referencing the map with respect to the digitising surface; a cursor which is movable with respect to the referenced map and the digitising surface; means for determining the position of the cursor with respect to the digitising surface in terms of the digitising surface""s co-ordinate system; means for processing the current wide-area co-ordinate position and the conversion data to determine the current position in terms of the digitising surface""s co-ordinate system and/or for processing the cursor position and the conversion data to determine the cursor position in terms of the wide-area co-ordinate system; and means for annunciating to a user the current position in terms of the digitising surface co-ordinate system and/or the cursor position in terms of the wide-area co-ordinate system; wherein the referencing means comprises means for registering the or each datum point of the map medium with respect to the digitising surface.
These latter features may be provided in an apparatus which does not possess the other features of the first and second aspects of the invention. Accordingly, a third aspect of the present invention is concerned with a position locating apparatus, for use with a traditional map having its own co-ordinate system distinct from a wide-area co-ordinate system and for use with conversion data associated with the map from which the relationship between the map co-ordinate system and the wide-area co-ordinate system can be determined, the apparatus comprising: a digitising surface having its own co-ornate system; means for referencing the map with respect to the digitising surface; a cursor which is movable with respect to the referenced map and the digitising surface; means for determining the position of the cursor with respect to the digitising surface in terms of the digitising surface""s co-ordinate system; means for receiving the conversion data; means for receiving transmissions from a wide-area position transmitting system and determining therefrom the current position of the transmission receiving means in terms of the wide-area co-ordinate system; means for processing the current wide-area co-ordinate position and the conversion data to determine the current position in terms of the digitising surface""s co-ordinate system and/or for processing the cursor position and the conversion data to determine the cursor position in terms of the wide-area co-ordinate system; and means for annunciating to a user the current position in terms of the digitising surface co-ordinate system and/or the cursor position in terms of the wide-area co-ordinate system. Such an apparatus is known from WO-A-87/07013 mentioned above. The third aspect of the invention is characterised in that: the apparatus is for use with such conversion data from which the relationship been the map co-ordinate system and at least one datum point of the medium on which the map is formed can be determined; and the referencing means comprises means for registering the or each datum point of the map medium with respect to the digitising surface. Thus, by making use of the conversion data and the registering means, referencing of the map with respect to the digitising surface can be greatly facilitated.
Preferably, the annunciating means is operable to annunciate the current position by indicating a required direction of movement of the cursor towards that position. Also, preferably, storing means is provided for storing a target position; the processing means is also operable to calculate the distance between the stored position and the current position and/or the bearing of the stored and current positions relative to each other; and the annunciating means is also operable to annunciate the calculated distance and/or bearing.
A fourth aspect of the present invention is concerned with a map having: its own co-ordinate system distinct from a wide-area co-ordinate system; and conversion data associated therewith from which the relationship between the co-ordinate system of the map and a wide-area co-ordinate system can be determined. As will be appreciated from the above, such a map is known from WO-A-95/22742. The fourth aspect of the invention is characterised in that: the map is one of a series of such maps; and the conversion data is collectively provided for all of the maps in the series. Accordingly the maps can be used in a system which can indicate to the user which of the maps to use.
Preferably, the area covered by each map can be determined from the conversion data. Some portions of the maps may overlap. Not all of the maps need be to the same scale, and in this case the conversion data preferably takes into account the different scales of the maps. The maps in the series may be bound together in the form of an atlas. When used with the apparatus described above, the apparatus can then tell the user to which page of the atlas to turn, and where on that page to look. The conversion data may be provided on or in the maps or atlas, for example in the form of a bar code or magnetic stripe printed on the map or inside cover of the atlas, or a smart card forming an additional page to the atlas, or which is removably inserted in a pocket or the like on the map or in the atlas. The conversion data includes at least one parameter related to the cartographic projection(s) of the maps, so that the system can accurately locate positions on maps employing different cartographic projections. In one embodiment, the conversion data is machine-readable, and the data receiving means of the apparatus may then comprise means for reading the machine-readable data. Alternatively, the conversion data may be provided as user-readable encoded text, and the data receiving means of the apparatus may then comprise means (such as a keypad) to enable a user to enter the encoded text and means for decoding the entered text.
A fifth aspect of the present invention provides a position locating system, comprising: an apparatus according to any of the first to third aspects of the invention; a traditional map having its own co-ordinate system distinct from a wide-area co-ordinate system; and conversion data associated with the map from which the relationship between the map co-ordinate system and the wide-area co-ordinate system can be determined.
A sixth aspect of the present invention provides a position locating system, comprising: an apparatus according to any of the first to third aspects of the invention; and a series of maps and associated data according to the fourth aspect of the invention.
In the fifth or sixth aspect of the invention, when the fine position annunciating means comprises a graphical display, the display is preferably substantially smaller in area than the or each map.
In accordance with a seventh aspect of the present invention, there is provided a data carrier per se associated with a series of maps and containing data from which the relationship between the co-ordinate system(s) of the map and the wide-area co-ordinate system can be determined, the data being machine-readable or being encoded user-readable text.
It may be appreciated from the above that at least certain embodiments of the invention provide the advantages over the known systems described above that; (1) there is no need for a digitising surface or the like, although in one version of the invention a digitising surface may be employed; (2) there is no need for a graphics display which is as large as the map; (3) traditional maps can be used, the only requirement being the additional data associated with the map, this being possible at low cost; (4) the user does not have any difficulty in selecting the appropriate map; (5) the user does not need to concern themself with latitude and longitude, but instead coordinate data is provided which is more relevant to the map being used. Using the example given above, instead of (or in addition to) being presented with the latitude and longitude co-ordinates (51xc2x030xe2x80x259xe2x80x3N, xe2x88x920xc2x006xe2x80x234xe2x80x3E), the user might instead be presented with the abbreviated OSGB grid block for the position on Sheet 176, i.e. xe2x80x9c(31, 81)xe2x80x9d or with the abbreviated higher resolution grid reference xe2x80x9c(312, 815)xe2x80x9d; and (6) referencing is carried out simply by entering the data associated with the map.